SEKONIC L-858D-U – HSS Light Meter Now Available



The Sekonic Speedmaster L-858D-U are the first light meters capable of measuring HSS flash bursts, as well as flash durations with a graphic display. And they are available now from $599.

Featuring a 2.7″ full color touch screen display, and all weather design, the L-858D-U also bring back interchangeable wireless radio modules, currently available for Elinchrom, Phottix, and PocketWizard.

The L-858D-U also feature an expanded measuring range and sensitivity, now capable of functioning in very low light conditions.

And with HSS measuring capability, shutter speeds to 1/16,000s are now supported for flash readings.






  • HSS Flash Measurements
  • Flash Duration Measurements
  • Optional Radio Transmitter Modules for Elinchrom, Phottix, & PocketWizard
  • 2.7” Color Dot Matrix Touch Screen Interface
  • Exposure Profiling
  • Extended ISO Range ISO 3 to ISO 13,107,200 + ISO 850
  • Expanded Shutter Speed Range 30m – 1/16,000s for Flash Light
  • Expanded Shutter Speed Range 30m – 1/64,000s for Ambient Light
  • Full HD Cine & CINE mode: 1 to 1000 f/s and 1° to 358° Shutter Angle
  • Connectivity with MAC/PC DTS Software for Firmware Upgrades, Custom Settings, & Exposure Profiling
  • Weather Sealed Design




HSS Flash Reading


The Sekonic L-858D-U are the first flash meter capable of measuring the short stroboscopic flash burst used in HSS (High Speed Sync).

With HSS fast becoming a must have feature, this helps in making off-camera HSS technology even more practical for users, who no longer have to rely on trial and error (or chimping) to set manual HSS flash exposures.

For multi light set ups in particular this ability can be quite a big advantage.




Flash Duration Measurements


Another significant new development with the introduction of the L-858D-U is the ability to measure flash durations, or “burn time”, and show results from t=0.1 to 0.9.

As well as providing a graphic display of the flash curve.

No longer do you have to rely on manufacturers often limited flash duration specs to know what your strobes motion freezing capability really is at certain power levels.

Or how the flash is likely to react when using Long Duration Sync methods etc. It can be very interesting to be able to see what your strobes are actually doing.






Wireless Radio Modules


The L-858D-U also bring back interchangeable radio modules, currently available for Elinchrom, Phottix, and PocketWizard.

So you won’t need a different light meter for each flash system (as the popular L-478D series meters require).




Remote control ability from the meter varies depending on the system, from simple triggering to full Remote Manual power control, and even modelling light power control –




Flash Analyzing Function


Like previous higher end Sekonic light meters, the L-858D-U also feature a Flash Analyzing Function, which measures ambient and flash simultaneously and automatically indicates the percentage of flash in the total exposure.

The digital display indicates the camera settings, and an analog display shows the relationship between ambient and flash, and the total exposure.




Data Transfer System

Because every digital camera, lens, and software is unique in its capability to capture and process light, Sekonic’s Data Transfer Software allows quick dynamic range mapping and camera/meter calibration for precise control.

The system can create and store up to ten camera exposure profiles with Sekonic, X-Rite, or datacolor, brand calibration targets.

Firmware updates and custom setting can also be enabled through the Sekonic Date Transfer Software (for Mac and PC).




The L-858D-U’s weather sealed case also provides a standard 1/4″ and 3/8″ threaded mounting point in the base.













The Sekonic SPEEDMASTER L-858D-U are available now from $599 –

Adorama, EbayAmazonB&H Photo

L-858D (Worldwide version available outside the USA) –

Amazon UK


Radio Modules are available separately.


Sekonic – Website


  1. 4 years ago

    Would love for Godox to come up with a radio module for their system. Any chance that’s in the works?

    • Author
      Flash Havoc 4 years ago

      Hi John,

      I’m not really sure. Separately both Godox and Sekonic sound positive about the idea, though I don’t know if its even been discussed between them.

      • Jeffrey 4 years ago

        If enough of us ask for it on sites like these they will hear and respond accordingly.
        So please sekonic and godox makevme a module.

    • Germaine 4 years ago

      Godox/flashpoint Adorama (whoever it is) please make the module happen with Sekonic

  2. Andrew 4 years ago

    I’ll add my call for a Godox module… that would convert me into a buyer for the light meter.

  3. bob 4 years ago

    I did not get the feeling that Sekonic or Godox had thought about it when talking to them but there is an alternative if he received the level of interest and I have been using the meter for 2 months and am really happy with it (managed to buy from Holland well before it was available in the UK)


    • Jeffrey 4 years ago

      Does this work with godox Bob?

      • Author
        Flash Havoc 4 years ago

        Jeffrey, I picked up and L-858D-U myself as well, so I’ll soon find out once I’ve had a chance to get familiar with it.

      • bob 4 years ago

        No, I have talked to him and it would only be a basic transmitter but he needs a decent volume of requests to consider

    • Author
      Flash Havoc 4 years ago

      Thanks Bob,

      I talked with Sekonic and I don’t think third parties will be able to create their own radio modules for the L-858D and future Sekonic models. Not with any remote control ability anyway, becasue the function is in the light meter interface itself. A simple fire signal may be possible, I’m not sure.

      EDIT – To be clear I was meaning third parties like Triggerwizard mentioned above won’t be able to create modules with any remote control ability – on their own, and without co-operation with Sekonic.

  4. Jeffrey 4 years ago

    I guess we will just have to keep pressuring Sekonic then.

    • Author
      Flash Havoc 4 years ago

      It sounds like the ball is more in Godox’s court at this stage, they will need the motivating.

      • Andrew 4 years ago

        So, is there anything we the humble readers can do?

        This is one area Godox will be lacking compared with Elinchrom and Phottix options.

        • Author
          Flash Havoc 4 years ago

          I’ll have to wait and see what Godox’s response is to this. I’ve told them people are wanting to start a petition for Godox / Sekonic integration.

          • Ales Tomis 4 years ago

            I would definitely sign this petition. I would buy this meter if Godox module is inside.

  5. Author
    Flash Havoc 4 years ago

    I’ve been experimenting with the L-858D-U now and the HSS measurement does work well.

    There are some major catches though, particularly with Godox.

    Firstly the HSS measurements only work in Cordless mode on the meter (that’s where there is no cord or radio connection to the flash, the meter simply waits to see the flash fire, and when seeing the light takes a reading).

    The problem with the recent Godox X system lights though, is that they do not produce the HSS pulses which triggered via their test fire button, or the test fire button on the X1T transmitter (even if its mounted on the camera). So you need to actually fire the camera shutter each time (with X1T transmitter mounted on top) to take a reading!

    Other strobes like the Orlit RT 610 for example do fire HSS pulsed via their test fire button. So that’s much easier, though they have another issue –

    The L-858D-U can only measure HSS results down to 1/4 power on the RT 610. That’s because to acheive low power levels in HSS mode, the RT 610 flash curve has a big short spike at the start (like a pre-flash), and then the continual small pulses which form the constant light follow. The small pulses are less than 10% (t0.1 mark) of the full flash pulse though, so it appears the meter is likely being confused by the first large pulse, and just reads as “Under”.

    The Godox strobes do have this issue as well, though mainly only at the lowest power levels where its not that much of an issue.

    Strobes using the Long Duration Sync method like the original RoveLight HD-600B trigger and measure fine. Though as you would expect with a gradient across the frame, the meter can only provide an estimate of roughly what the correct exposure should be in the brightest part of the frame for example.

    The L-858D-U flash duration meter works very well though, and its great to be able to see whats going on with the HSS pulsed for example, even when the meter can’t provide an exposure level for them.

    This is all even more reason though why Godox for example should be collaborating with Sekonic to help make the HSS reading more practical with their strobes.

    • Jeffrey 4 years ago

      Have you sent these findings to Godox & Sekonic?

      • Author
        Flash Havoc 4 years ago

        Yes I’ve been talking a bit with Sekonic. I only just mentioned my comments above to them earlier today.

        Still waiting on an initial response from Godox though. And they will likely be off to the China P&E trade show now as well.

  6. Sal 4 years ago

    I too would buy the meter if there was a good integration with Godox flashes (and possibly Hensel in Studio).

    Not being able to use the test button on the Godox-X1-System (but instead firing the camere) is a big no-go for me. 🙁 🙁
    Otherwise I might use light-meter + sender off camere (not ideal, but works).

    Just to clarify…
    Let’s say I have a situation, where firing the camera emitts a HSS-Signal via the X1-sender. When I press the Test-Button, the flash produces just a normal (non HSS) flash?
    I guess when on camere it is e.g. manual 1/4 HSS, the test button will create a normal 1/4 flash?
    By the way, what’s the test-flash-power when in TTL-mode?

    Thanks a lot!!!

    • Author
      Flash Havoc 4 years ago

      Hi Sal,

      Yes that is correct. Even if the X1 transmitter is on the camera hotshoe the test fire button still produces a normal (non HSS) flash.

      Yes manual 1/4 HSS would test fire as normal 1/4 flash power.

      The test flash in TTL mode is just a low power flash. I haven’t measured the Godox flashes, though 1/32 power is often used, as that was the main option (other than full power) previously with TTL speedlites.

  7. DanielB 4 years ago

    What if the Godox transmitter were on a Godox receiver and the test button on the receiver was pushed, would that trigger a real HSS flash?

    • Author
      Flash Havoc 4 years ago

      Hi DanielB,

      I think we are in business!

      Placing a Godox X1T transmitter on a Godox X1R receiver didn’t work. Though I kept thinking there had to be some way to do this, and it turns out firing the Godox strobes via their PC Sync port, or the XTR-16 communication port, does the trick test firing the strobe in HSS mode!

      So the simplest way I could make this all work and still have remote power control of the strobe was to use the clip-on XTR-16 receivers attached to the strobe. That way you have remote power control, triggering, and test fire, from the X1 transmitter as normal. (Its just the added clip-on receiver that is a small inconvenience).

      Another option is to attach an X1R receiver to the flash via PC sync cord. Though remote power control gets more complicated then, because you need to set the strobe to a different channel than the receiver, and switch channels back and forth on the transmitter between test firing and power control. And if you accidentally press the X1 test fire while on the strobe channel, the strobe will drop out of HSS mode again.

      So the XTR-16 receiver appears to be the neatest solution for now.

      • Germaine 4 years ago

        Thanks!! I am using the X1R option. This method works great but for some reason the meter reading does not match the actual flash reading when shot. It is only off by 3-5 tenths of a stop. Overall it still is a great option. thanks again!

  8. XJ 4 years ago

    I bought this L-858D about a month ago and I wanted to use it for HSS work. I use a Streaklight/godox AD360 with the R2 transmitter.

    The transmitter is connected to my camera, and I have a remote shutter trigger connected to the sync port of my camera. As advised by sekonic, when using HSS set the Pre-Flash from 0 to 1. Also tried going all the way to 5.

    I would then set my shutter speed around 1/320-1/8000 and ISO100, when I try to take a HSS reading with dome in/out, I would just get a “- -” or “under”.

    Here’s how I try to measure..

    1. Subject is backlit by the sun, Streaklight 360 with 18″ octabox on right of subject, camera on about a 3 feet away from streaklight 360. With dome out, I point the dome towards the camera and get a reading of “- -” or “under”

    2. Same setting in #1, I put the dome in and got a reading of F4, I then adjusted the shutter and until I got a reading of F1.8 which is my desired Fstop. I set the light meter to Dome out again and got a reading of F1.8. Set it back to Dome In and got “- -” and “under”

    3. Did the same test as #1 and #2, however this time subject is side lit by the sun on the left, and Streaklight is in front right.. I got the same inconsistency as #1 and #2.

    Any idea if what Im doing anything wrong here?

    • Mike 4 years ago

      must trigger the flash by triggering the camera


    • Author
      Flash Havoc 4 years ago

      Hi XJ,

      I haven’t had a chance to look at the Streaklight yet, though as I mentioned in my comment further above, some strobes won’t provide a HSS reading mainly at their lower power levels. That was the case with the AD600 and AD200. The meter reads “under”.

      If you look at the flash duration graph curve in HSS mode at those lower power levels though you can see why this is likely happening. There is a big short spike at the start, and then the continual small pulses which form the constant light follow. The small pulses are less than 10% (t0.1 mark) of the full flash pulse though, so it appears that may be the reason the meter does not recognize them and just reads as “Under”. Or maybe because they are too low to measure in relation to the first large peak spike.

      I didn’t know about Sekonic’s suggestion to set the Pre-Flash from 0 to 1, though that makes sense if that can possibly help to ignore the first big spike I mentioned above.

  9. C. Stephen Hurst 4 years ago

    I still don’t understand how you tell the AD600 to test fire in HSS mode via the trigger, even with the XTr-16 plugged in. How does the flash know what pulse (HSS or Regular) to fire?

    A) Do you manually engage the HSS at the Strobe and then press the test button or

    B) Have the trigger on camera. Fire off a shot that would engage HSS with one hand while holding the meter in the other?

    Either of these solutions seem cumbersome.

    • Mike 4 years ago

      You have to trigger the camera with the X1 or X32 on as the test button on the flash does not send the HSS pulse


    • Author
      Flash Havoc 4 years ago

      Hi Stephen,

      If using the XTR-16 its your option A, you need to set the HSS mode ON, directly on the strobe. Then you can press the test fire button on the transmitter, and the strobe will fire with HSS pulses.

      I’m not sure why you mention that sounds cumbersom? Isn’t that how you would do it even if not needing the XTR-16 receiver to do this.

      (Needing to use the XTR-16 receiver is a bit annoying, because that shouldn’t be necessary).

  10. Hans 4 years ago

    I would love a Godox module… that would make me a buyer for the light meter.

  11. Jeffrey 4 years ago

    Any response from godox as yet?

    • Author
      Flash Havoc 4 years ago

      Unfortunately no. Flashpoint prompted them for a reply as well and still nothing.

      All you can do is just keep emailing Godox until they hopefully eventually get the message.

  12. Guus 4 years ago

    And what about a new Profoto transmitter like in the 758?
    hope soon it wille come!
    any sound yet?

  13. XJ 4 years ago

    Does this light meter’s HSS functionality work well with the Orlit 610?

    • Author
      Flash Havoc 4 years ago

      Hi Xj,

      With the Orlit RT 610 the HSS metering appears to work ok, though only down to 1/4 power level on the strobe. Bellow that the meter just reads “Under”.

      That’s likely because (looking at the flash duration graphs at lower power levels in HSS mode) there is a big spike at the start of the flash pulse (like a pre-flash), and the meter is likely reading the spike and not the continuing HSS pulsed that follow.

      Update – I just read your post further above mentioning that Sekonic said to set the pre-flash from 0 to 1 (to ignore the first pre-flash). I do think I did that after originally reading your post and it didn’t help, though I’ll have to check this again to make sure).

      • XJ 4 years ago


  14. Jeffrey 3 years ago

    Any new developments between Sekonic and Godox?

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